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Luke B Winternitz

Publications and source records attributed to Luke B Winternitz.

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Autonomous Navigation of a Lunar Relay Using GNSS and Other Measurements

NASA’s Lunar Communications Relay and Navigation Services (LCRNS) project will establish a relay constellation at the Moon to provide the south pole region with communications and position, navigation, and time (PNT) services. These services will require highly accurate knowledge of position, velocity, and time (PVT) for each relay. This paper explores one approach for performing onboard PVT estimation, the LCRNS PNT Instrument (LPI). This paper considers different configurations of the instrument, specifically different measurement types and clocks, and the resulting navigation performance. Simulation results are first shown for an instrument configuration that uses GPS pseudorange and Doppler measurements with a highly sensitive GPS receiver (i.e., an acquisition and tracking threshold of 23 dB-Hz) and a chip-scale atomic clock (CSAC). The importance of Doppler, clock quality, receiver sensitivity, and optical navigation is examined through comparison of these results to other instrument configurations. Clock quality (i.e., stability) is the strongest determinant of achievable performance, and the inclusion of GPS Doppleralso has a significant effect. Finally, simulation results are compared to two laboratory tests: first a case that includes GPS receiver hardware in the loop, then a case that includes optical navigation and filter flight software in the loop. These agreeclosely with the simulation results and provide evidence the simulation is accurately modeling the instrument under development.

Benjamin W Ashman↗
NASA NTRS2022

A High-fidelity Performance and Sensitivity Analysis of X-ray Pulsar Navigation in Near-Earth and Cislunar Orbits

Millisecond X-ray pulsars are rapidly rotating neutron stars that emit broadband electromagnetic radiation, including X-rays. These emissions can appear as pulsations to distant observers with long-term stabilityrivaling laboratory atomic clocks. The concept of using X-ray pulsars for navigation, commonly referred to as XNAV, has a long history in the research literature. Notably, in 2017, NASA’s Station Explorer for X-ray Timing and Navigation (SEXTANT) mission,a technology enhancement to the Neutron Star Interior Composition Explorer, made a successful on-orbit demonstration of XNAV on the International Space Station (ISS) in Low-Earth-Orbit. This paper investigates the performance of XNAV in Earth and lunar regimes using a new high-fidelity XNAV analysis tool that builds on tools developed for SEXTANT and uses recent updates to the Goddard Enhanced Onboard Navigation System flight software. Specifically, we study the use of XNAV in an ISS-like orbit for comparison with SEXTANT results, in a highly-inclined geosynchronous orbit, and in an Earth-Moon L1 libration point Near Rectilinear Halo Orbit similar to that proposed for the planned lunar Gateway space station. This paper provides a high-level description of the XNAV analysis tool, baseline predicted performance results, selected sensitivity analyses, and conclusions.

Luke B Winternitz↗
NASA NTRS2022

Terrain Relative Navigation in a Lunar Landing Scenario Using autoNGC

NASA Goddard Space Flight Center is developing Autonomous Navigation Guidance and Control (autoNGC) as a flight software system for future onboard use for missions in a variety of orbital regimes, including cislunar space and beyond. This paper describes processor-in-the-loop (PIL) testing using a lunar landing scenario with terrain relative navigation (TRN) and weak-signal GPS. We give an overview of the autoNGC project and describe preliminary navigation simulation results. We also describe the TRN PIL tests on a flight-like development board, using simulated images rendered from Lunar Reconnaissance Orbit high-resolution digital terrain models. The navigation simulations show that weak-signal GPS combined with TRN during a descent from a low lunar parking orbit results in sufficiently low navigation uncertainties to support such a mission profile independent of ground-based navigation. The PIL tests show that onboard image processing and landmark correlation is achievable at a sufficiently high measurement rate.

Michael A Shoemaker↗
NASA NTRS2021

Applications and Benefits of GNSS for Lunar Exploration

This paper explores the role of Global Navigation Satellite Systems (GNSS) in NASA's lunar exploration plans. Robust position, navigation and timing (PNT) at the Moon will rely on a variety of measurement sources, each with its own advantages and disadvantages. The best navigation solution will depend on mission type, the phase within each mission, the state of lunar infrastructure development at the time and a host of other considerations. No single method will provide all PNT for all scenarios, but GNSS offers a continuously available, flight-proven source of navigation and timing with unique features that make it a valuable option. As NASA launches a new era of lunar exploration missions in 2021, development of the supporting navigation architecture is underway. This paper describes the role GNSS could or will play in the components of NASA's lunar exploration plans: the Artemis missions designed to return humans to the lunar surface, the Gateway platform orbiting near the Moon that will host astronauts as well as science and technology payloads, and the robotic lander missions administered by the Commercial Lunar Payload Services (CLPS) program. GNSS-based autonomous navigation has the potential to dramatically expand lunar exploration capabilities. Through the use of GNSS and GNSS-like augmentations, navigation performance could be improved while simultaneously reducing operational complexity relative to conventional, ground-based navigation methods. As NASA begins to implement its lunar exploration plans this year and assemble the enabling communications and navigation infrastructure, GNSS will provide an important part of the diverse measurements required for robust lunar PNT.

Benjamin W Ashman↗
NASA NTRS2017

Global Positioning System Navigation Above 76,000 km for NASA's Magnetospheric Multiscale Mission

NASA's Magnetospheric Multiscale (MMS) mission, launched in March of 2015, consists of a controlled formation of four spin-stabilized spacecraft in similar highly elliptic orbits reaching apogee at radial distances of 12 and 25 Earth radii (RE) in the first and second phases of the mission. Navigation for MMSis achieved independently on-board each spacecraft by processing Global Positioning System (GPS) observables using NASA Goddard Space Flight Center (GSFC)'s Navigator GPS receiver and the Goddard Enhanced Onboard Navigation System (GEONS) extended Kalman filter software. To our knowledge, MMS constitutes, by far, the highest-altitude operational use of GPS to date and represents a high point of over a decade of high-altitude GPS navigation research and development at GSFC. In this paper we will briefly describe past and ongoing high-altitude GPS research efforts at NASA GSFC and elsewhere, provide details on the design of the MMS GPS navigation system, and present on-orbit performance data from the first phase. We extrapolate these results to predict performance in the second phase orbit, and conclude with a discussion of the implications of the MMS results for future high-altitude GPS navigation, which we believe to be broad and far-reaching.

navigation↗
NASA NTRSDate not supplied

NavCube3-mini Lunar GNSS Receiver

This paper describes development and testing of NASA Goddard Space Flight Center’s new NavCube3-mini (NC3m) spaceborne, weak-signal GNSS receiver, which targets all Earth orbit regimes with special focus on lunar applications. NC3m derives from the ground-breaking Magnetospheric Multiscale (MMS) mission Navigator GPS receiver. The MMS-Navigator (launched 2015) holds a Guinness World Record for highest altitude GPS fix and is currently in a highly elliptic orbit with a 29 Earth radii apogee, nearly half lunar distance. NC3m has reduced size, weight, and power compared to the MMS-Navigator, making it suitable for smallsat applications, and adds multi-frequency and multi-GNSS capabilities, among other improvements. A NC3m engineering test unit was subjected to and successfully completed a comprehensive Technology Readiness Level 6 (system/subsystem model or prototype demonstration in a relevant environment) testing campaign in the second half of 2022. This involved high-fidelity simulations in LEO, GEO, and lunar regimes and full environmental testing, including vibration, thermal vacuum, and electromagnetic compatibility. An overview of the NC3m receiver, the test setup, and a sample of results is presented. The results include predicted performance at high-altitude and in the lunar regime.

NavCube3↗